Mercedes AMG F1 W07

[FoxHound]

The Mercedes cars from 2011 (W02) onwards have displayed plenty of roll characteristics.
Mercedes more than most suffered with setups in the period running 2011-13.

From general observation the car rolls through the corner, leaning on the loaded section, which in turn lowers the front wing on the loaded side.
The same rings true for the rear of the car, with the loaded side of the floor being closer to the ground than the unloaded part.

The question is, whats the gain?

Drievablity. Weight transfer must also match the movement of air under the car to give good balance. My theory is that the air flow on either side under the car is starved depending on the radius of the turn and speed of the car. So the floor must pitch and roll with those changes to maintain some sort of orderliness of the flow and hence stability.

Seems plausible enough. But the increase in variables is exponential with rake surely? Or would some rake actually help the effect?

[bhall II]

Looks like something is broken - anti-roll bar? Left side suspension travel is pulling on the bodywork, and that much contact with the circuit would almost certainly result in a near-complete loss of underbody downforce.

[chuckdanny]

Yes, i think this particular moment is not representative of the way its supposed to work. A brutal change of direction here due to the high speed and very closed turn exit, plus hitting the curb, what we see is the reception of a jump basically together with big load transfer.

Considering the benefit of being closer to the ground at middle to high speed for the floor as suggested by comments of jenson button. What he said was that higher rake is more stable hence giving a big confidence boost for the drivers as we see also with the redbull drivers. He was talking about the braking phase which is a highly transient phase.
But still lower rake at high/mediumhigh does not as i thought reduce downforce as it is supposed to reduce drag and maybe the answer to this is this picture from the pirelli test of 2017 tires.

The way they increase downforce to match more or less what should be 2017 downforce level, as far as i can see the main modifications are those two little hanging pieces* that reduce side inlet and isolate a little more positive pressure potential from negative pressure potential hence accelerating the speed of vortices increasing induced downforce. Well its my interpretation it maybe wrong. So i suppose its possible to have this reduced inlet effect and as the rotation is in roll it doesn't affect as much the rake as the car rotate over a longitudinal cone.
So more peak downforce with lower rake at high speed which redbull achieve with non linear softer spring at the rear and more stability under braking hence confidence in the rear end staying in the back position which is usefull.
It seems that high rake at low speed benefit essentially the front wing as there problem is understeer. Softer spring at the back allow more load tranfer on the outside front wheel hence less understeer.



* a configuration i tested on a transat chair in ground effect

[SectorOne]

and that much contact with the circuit would almost certainly result in a near-complete loss of underbody downforce.

He´d be replacing Heineken as a sponsor on the wall if almost all down force vanished

[bhall II]

and that much contact with the circuit would almost certainly result in a near-complete loss of underbody downforce.

He´d be replacing Heineken as a sponsor on the wall if almost all down force vanished

[timbo]

and that much contact with the circuit would almost certainly result in a near-complete loss of underbody downforce.

He´d be replacing Heineken as a sponsor on the wall if almost all down force vanished

So, you think that immediate shift of aerobalance to the front (inevitable upon complete loss of underbody DF) would not result in a crash? Even few percent of shift of DF focus can make car undriveable.
IMO the picture (and the fact that there were no "moments" for the MERC cars this weekend) clearly means that floor retained significant part of DF it normally produces.

[chuckdanny]

He´d be replacing Heineken as a sponsor on the wall if almost all down force vanished

So, you think that immediate shift of aerobalance to the front (inevitable upon complete loss of underbody DF) would not result in a crash? Even few percent of shift of DF focus can make car undriveable.
IMO the picture (and the fact that there were no "moments" for the MERC cars this weekend) clearly means that floor retained significant part of DF it normally produces.

Maybe not. Trying to figure out how it is possible : the peak downforce necessary was there just before this disruptive moment. At the time of the picture the car has already rotated enough, it is inline. Suspension has memory, the downforce resulted in a compression and a dynamic equilibrium in a higher energy state. While the diffuser see a disruption of the flow it takes time, there is a delay. Suspension delay are much faster than flow disruption delay.
Hiting the curb transfer energy to the outside tire especially when they are connected.
So the tires don't need anymore the very peak downforce at this moment and the rebound of suspension which comes from the potential energy release its memory of past downforce and mass transfer which compensate the aerodynamic load loss.
Of course we can ask wether the rebound doesn't push the rearend upward instead. I think it does both but we must had the fact that its a reception of a jump in a turn so the lumped mass is "heavier" due to centrifugal forces and moments due to the impact jounce. While the flow slowly recover...
Its a complex system of cause and effect that allow rosberg to still be in one piece.

[bhall II]

A one-off transient loss of rear downforce on corner exit isn't necessarily the end of the world, because a skilled driver will usually be able to catch the resultant oversteer. It (obviously) becomes (much) more problematic if it's a constant feature of the car's handling characteristics.

[timbo]

A one-off transient loss of rear downforce on corner exit isn't necessarily the end of the world, because a skilled driver will usually be able to catch the resultant oversteer. It (obviously) becomes (much) more problematic if it's a constant feature of the car's handling characteristics.

Well, Senna @ Tamburello?

I would, however, agree that we know too little and trying to get too much info from a single photo is not very reasonable.
However, few things are clear -- Merc cars have pronounced roll attitude (probably more than other cars), sparks flying from FW endplates are not uncommon, they clearly are getting away with it.

[bhall II]

Well, Senna @ Tamburello?

Apples and oranges. Beyond that...


via Willem Toet

[timbo]

Apples and oranges.

You have apples to apples examples to back up your claim? My point is we can only guess here.

Beyond that...

http://i.imgur.com/9T8iSOt.jpg
via Willem Toet

Those are nice graphs, but how it all applies to Merc car (and is there anything "clever" they do compared to other teams) is again only a subject of guessing.

[bhall II]

The apples and oranges comparison is the comparison to Senna's crash, because he lost control (at 305kph) while rotating his car through the apex of a corner; my statement was explicitly limited to corner exit, i.e. after most rotation has already occurred. (And if Rosberg's adventure took place at Degner, his pace was likely slower by some 45kph.)

If you ever come up with a design for a passive motorsport diffuser that can withstand a sharp reduction of dynamic pressure while maintaining suction at the same time, don't tell anyone about it until you've managed to secure a patent, and please invite me to Stockholm for your Nobel Prize ceremony. I'm pretty sure you will have discovered the ingredients necessary to achieve perpetual motion.

(I know I'm an ass. )

Here's another reason why the photo is a depiction of unintended consequences...

The phenomenon of standing waves in tyres occurs at high speeds, when a vehicle speed exceeds a certain
‘critical velocity’. Then quite intensive flexural waves travelling around the circumference of the tyre
emerge from the trailing edge of the contact patch. To the observer these waves in the tyre appear to be
stationary, but they are in fact travelling around the tyre at the same speed as the rotation of the tire. This
is why these waves are often referred to in the literature, not quite correctly, as ‘standing waves in tyres’.
Since this term is already well established, we will use it as well.

The large displacements of the tyre surface due to the generated standing waves introduce a large amount
of energy into the tyre material, which can lead to a quick tyre failure or at the very least can severely
affect the handling of the vehicle. Since the phenomenon of standing waves is usually observed at high
vehicle speeds, clearly aircraft tyres, race car tyres and to a lesser extent passenger car tyres are likely to
experience it. Note that manufactured tyres normally have a speed rating to indicate the experimentally
established maximum vehicle speeds below which they can be used safely. However, the real vehicle
speeds at which the standing waves occur can be substantially lower due to poor maintenance of the tyre
and/or due to its under-inflation as well as because of other conditions, such as the load on the tyre.

It never occurred to me that my initial comment might be controversial, else I may have framed it a bit differently. Sorry about that.

[trinidefender]

The apples and oranges comparison is the comparison to Senna's crash, because he lost control (at 305kph) while rotating his car through the apex of a corner; my statement was explicitly limited to corner exit, i.e. after most rotation has already occurred. (And if Rosberg's adventure took place at Degner, his pace was likely slower by some 45kph.)

If you ever come up with a design for a passive motorsport diffuser that can withstand a sharp reduction of dynamic pressure while maintaining suction at the same time, don't tell anyone about it until you've managed to secure a patent, and please invite me to Stockholm for your Nobel Prize ceremony. I'm pretty sure you will have discovered the ingredients necessary to achieve perpetual motion.

(I know I'm an ass. )

Here's another reason why the photo is a depiction of unintended consequences...

http://i.imgur.com/8LsSORD.png

The phenomenon of standing waves in tyres occurs at high speeds, when a vehicle speed exceeds a certain
‘critical velocity’. Then quite intensive flexural waves travelling around the circumference of the tyre
emerge from the trailing edge of the contact patch. To the observer these waves in the tyre appear to be
stationary, but they are in fact travelling around the tyre at the same speed as the rotation of the tire. This
is why these waves are often referred to in the literature, not quite correctly, as ‘standing waves in tyres’.
Since this term is already well established, we will use it as well.

The large displacements of the tyre surface due to the generated standing waves introduce a large amount
of energy into the tyre material, which can lead to a quick tyre failure or at the very least can severely
affect the handling of the vehicle. Since the phenomenon of standing waves is usually observed at high
vehicle speeds, clearly aircraft tyres, race car tyres and to a lesser extent passenger car tyres are likely to
experience it. Note that manufactured tyres normally have a speed rating to indicate the experimentally
established maximum vehicle speeds below which they can be used safely. However, the real vehicle
speeds at which the standing waves occur can be substantially lower due to poor maintenance of the tyre
and/or due to its under-inflation as well as because of other conditions, such as the load on the tyre.

It never occurred to me that my initial comment might be controversial, else I may have framed it a bit differently. Sorry about that.

If you ever look at a car setup for drag racing you will notice similar waves in the tyre. Drag cars generally use the largest tyre possible with a fairly small rim size for a very large and flexible sidewall. On top of that there are bed lockers to keep the sidewall seated on the rim facilitating the running of very low pressure.

This flex is intended as it allows the tyre to flex more putting more tyre surface in contact with the road increasing grip (or traction as it is often referred to) during launch. Obviously this is a slightly different scenario however we see pretty much all the teams run as low pressure as allowed to increase the contact patch and traction.

This picture simply looks like it was a case of all the holes in a Swiss cheese model lining up; car may have bounced off of a curb, hard acceleration taking place and a fairly high G corner all done at the same time can end up with a picture similar to this. You can clearly see the tyre is flexing both inward and backward, probably as a result of hard acceleration out of a corner.

[Cold Fussion]

I'm pretty sure that photo is taken at degner 1 so you can rule out significant longitudinal acceleration and bouncing off a curb.

[bhall II]

If you ever look at a car setup for drag racing...

In drag racing, the wrinkles are predominantly in front of the contact patch and become something quite different at speed...



Maybe related. Maybe not. I have no idea. Apparently, the sidewalls of F1 tires are relatively stiff.

For what it is worth, vertical tyre stiffness (in N/mm) measured on a rig were as follows:

F4 : 219/250
GP3 : 250/289
GP2 : 284/336
FE : 325/371
F1 : 340/463

Which were the low profile tyres...?

The image below is from last year's Belgian GP, a race in which Vettel was forced to retire on the penultimate lap due to a sudden tire failure...



In Pirellispeak, those are called "cuts," and they occur if a driver exhales a bit more forcefully than usual.